1. Field of the Invention
The present invention relates to a stamp device provided with a stamp plate constructed from a porous base plate wherein an ink impermeable melted-solidified portion and an ink permeable non-melted portion are formed by selectively heating and melting a stamp surface of the porous base plate having open cells, and a support member which supports the stamp plate from a plane thereof, and more particularly to a stamp device with improved various stamping characteristics by regulating the viscosity of ink to be impregnated in the non-melted portion of the stamp plate into a predetermined range.
2. Description of Related Art
Heretofore, a number of proposals have been made regarding stamp devices each using a stamp plate constructed from a porous base plate formed of cellular plastic or rubber having open cells therein, on which an ink permeable non-melted portion and an ink impermeable melted-solidified portion are formed by selectively heating and melting a stamp surface of the porous base plate by means of a thermal head. The ink permeable non-melted portion is the portion where open cells are left according to the shape of mirror images and the like to be stamped. The ink impermeable melted-solidified portion is the portion where open cells in the portion excepting the above part forming the mirror images are melted and solidified to be sealed.
As the ink to be impregnated in the non-melted portion formed in the stamp plate, the ink made of organic solvent and dye melted therein is generally used. For example, polyglycol butyl ether or tripropylene glycol butyl ether, etc. is used as the organic solvent. Oil soluble dye is used as the dye.
However, regarding the ink to be used in the stamp devices to stamping characters and the like shaped on the non-melted portion of the stamp plate, the ink using polyglycol butyl ether or tripropylene glycol butyl ether, etc. as the organic solvent as mentioned above, the viscosity of the ink has not been taken much into consideration. The stamping characteristics required for this kind of ink are usually apt to be opposite between the ink having too low viscosity and the ink having too high viscosity. It is accordingly difficult to regulate the viscosity of ink to satisfy all stamping characteristics required for the ink. Under the present circumstances, sufficient study on the viscosity of ink has not been made yet.